The purpose of the trial is to evaluate the safety, efficacy and immunogenicity of up to 3 intramuscular injections of the Acne mRNA vaccine candidate at up to four dose levels in adult participants aged 18 to 45 years with moderate to severe acne.
This trial will consist of a Core Study followed by an optional Long-Term Extension (LTE).
The Core Study will consist of:
* Two cohorts evaluating the 2-administration regimen (Cohorts A): Sentinel Cohort A and Main Cohort A. * Two cohorts evaluating the 3-administration regimen (Cohorts B): Sentinel Cohort B and Main Cohort B.
Participants from Sentinel Cohorts A and B and from Main Cohort A will be invited to an additional 30-month follow up after completing their last planned Core Study visit to assess the long-term effects of the vaccine. Participants from Main Cohort B will be invited to another LTE study managed through a separate protocol.
Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests as judged by the investigator
Clinical diagnosis of moderate or severe facial acne vulgaris with Investigator's Global Assessment (IGA) score of Moderate or Severe (grade 3 or grade 4 on the 5-grade IGA scale) and ≥ 25 non-inflammatory lesions (ie, open and closed comedones) and ≥ 20 inflammatory lesions (ie, papules and pustules) and ≤ 2 nodulocystic lesions (ie, nodules and cysts)
Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within 6 months prior to the first study intervention administration; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
Known systemic hypersensitivity to any of the study intervention components; history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of mRNA coronavirus disease 2019 (COVID-19) vaccine
Active nodulocystic acne, acne conglobate, acne fulminans, secondary acne (eg, chloracne, drug-induced acne) or other forms of acne (eg, acne mechanica)
Use of any acne-affecting treatment without an appropriate washout period
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Treatment groupsSee each treatment group below.